NAME¶

json-doc - (JSON-parsing)

PURPOSE¶

Parse JSON text.

SYNTAX¶

json-doc <text> to <json> \


    [ status <status> ] [ length <length> ] [ noencode ] [ no-enum ] \


    [ error-text <error text> ] \


        [ error-position <error position> ] \


        [ error-line <line> ] \


        [ error-char <char> ] 
json-doc  delete <json>

DESCRIPTION¶

json-doc will parse JSON <text> into <json> variable, which can be used with read-json to get the data.

The length of <text> may be specified with "length" clause in <length> variable, or if not, it will be the string length of <text>.

The "status" clause specifies the return <status> number, which is GG_OKAY if successful or GG_ERR_JSON if there is an error. The number <error position> in "error-position" clause is the byte position in <text> where error was found (starting with "0"), in which case <error text> in "error-text" clause is the error message. You can also obtain the error's line number (with number <line> in clause "error-line") and the character position within that line (with number <char> in clause "error-char").

"noencode" clause will not encode strings, i.e. convert from JSON Unicode strings to UTF, nor will it perform any validity checks on strings. This may be useful as a performance boost or to pass along strings unencoded, however in most cases it is not needed.

"no-enum" clause will not include indexing of arrays in normalized names (with "[..]"), see read-json. This is useful if you want to check the path of each data element, and not worry about counting them; this happens often when using JSON in a structured way to transfer arrays when data elements repeat in a predictable fashion. Parsing of JSON is also faster with "no-enum".

The maximum depth of nested structures in JSON document (i.e. objects and arrays) is 32, and the maximum length of normalized leaf node name is 1024 (see read-json for more on normalized names). There is no limit on document size.

DELETING

To delete a JSON variable, use "delete" clause with the <json>. This will delete all memory associated with it, and the variable <json> itself.

EXAMPLES¶

Parse the following JSON document and display all keys and values from it. You can use them as they come along, or store them into new-hash or new-tree for instance for searching of large documents. This also demonstrates usage of UTF8 characters:

// JSON to parse
set-string jd unquoted = {"menu":\


    {"id": "file",\


    "value": 23091,\


    "active": false,\


    "popup":\


        {"menuitem":\


            [{"value": "New", "onclick": "CreateNewDoc with\uD834\uDD1Emusic"},\


            {"value": "Open", "onclick": "OpenDoc() with \uD834\uDD1E\uD834\uDD1E"},\


            {"value": "Close", "onclick": "\uD834\uDD1ECloseDoc()"}\


            ]\


        }\


    }\
}
// Parse JSON
json-doc jd status st error-text et error-position ep to nj
// Check parsing okay, if not display error details
if-true st not-equal GG_OKAY


    @Error [<<print-out et>>] at [<<print-out ep>>]


    exit-handler -1
end-if
// Display all data elements in order from top to bottom
start-loop


    read-json nj key k value v type t next


    if-true t equal GG_JSON_TYPE_NONE


        break-loop


    end-if


    @Key [<<print-out k>>]


    @Value [<<print-out v>>]


    @Type [<<print-out t>>]


    @--------
end-loop
@
// Delete JSON document
json-doc delete nj

The output would be:

Key ["menu"."id"]
Value [file]
Type [0]
--------
Key ["menu"."value"]
Value [23091]
Type [1]
--------
Key ["menu"."active"]
Value [false]
Type [3]
--------
Key ["menu"."popup"."menuitem"[0]."value"]
Value [New]
Type [0]
--------
Key ["menu"."popup"."menuitem"[0]."onclick"]
Value [CreateNewDoc with𝄞music]
Type [0]
--------
Key ["menu"."popup"."menuitem"[1]."value"]
Value [Open]
Type [0]
--------
Key ["menu"."popup"."menuitem"[1]."onclick"]
Value [OpenDoc() with 𝄞𝄞]
Type [0]
--------
Key ["menu"."popup"."menuitem"[2]."value"]
Value [Close]
Type [0]
--------
Key ["menu"."popup"."menuitem"[2]."onclick"]
Value [𝄞CloseDoc()]
Type [0]
--------

Note that if "no-enum" were used in json-doc, then all keys with arrays would not have "[..]", for instance the very last key above would be "menu"."popup"."menuitem"."onclick", i.e. there would be no indexing of arrays.

SEE ALSO¶

JSON parsing

json-doc read-json See all documentation